It has been the general practice to releasably secure a transmission and associated cross drive mechanism of a track-type vehicle to the main frame laterally within the sidewalls so that the transverse central axis of the cross drive mechanism is in precise alignment with the input axis of the final drives. The final drives typically have a plurality of gears for speed ratio reduction purposes, and are separately releasably secured to the outer surfaces of the sidewalls. There are several problems associated with such arrangements. Firstly, the main frame and the cross drive housing need to be very accurately machined to insure alignment of the axes. Secondly, the components are separately assembled or disassembled which is often time consuming because so many fasteners are used. Thirdly, in order to maintain alignment of the axes, the parts are assembled in a rigid metal-to-metal manner so that vexatious noises emanating from within the power train or generated at the track drive wheels are transmitted to the main frame and to the operator.
U.S. Pat. No. 4,506,757 issued to T. Matsumoto, et al on Mar. 26, 1985 relates to a track-type vehicle and is representative of the prior art. A longitudinally oriented transmission is connected to a cross drive mechanism having a pair of oppositely extending output shafts, and these components are releasably connected to the inside portions of the main frame as a module. The final drives are separately connected to the outside portions of the main frame so that considerable complexity is involved. The housing of the cross drive mechanism has opposite tubular bosses which are seated in directly upwardly facing semicircular recesses formed in the main frame, and clamps fit over the upper halves of the bosses to releasably hold them in place. The rearwardly located bosses of the housing are allowed to pivot and the front of the transmission is connected to the main frame by transversely oriented resilient bushing assemblies which resist torque loads about the cross drive axis. However, transmission induced noises can undesirably travel directly to the main frame through the metal-to-metal connections at the tubular bosses, and can travel from the track drive sprockets to the main frame directly through the final drives.
Accordingly, what is needed is an economical yet rugged mounting arrangement for a power train module including a cross drive mechanism that will allow testing of the module as a complete subassembly prior to being installed on the vehicle. And, the installation of the power train module on the main frame should be simple and convenient. In marked contrast, the assembly of the construction shown in aforementioned U.S. Pat. No. 4,506,757 requires that the transmission and cross drive mechanism be substantially vertically lowered into place; this unfortunately necessitates that a significant number of tractor components be removed in the region of the operator station to allow access to the main frame.
Also, what is needed is a mounting arrangement for a power train module that can allow a relatively economical main frame construction to be used.
And further, the power train module mounting arrangement should preferably include resilient connections to the main frame such as by elastomeric or rubber coupling assemblies for minimizing the transmission of noise from the power train module to the main frame and for minimizing the transmission of noise generated at the drive wheel by the track to the main frame.
And still further, the power train module should preferably locate the opposite final reduction gearing laterally inwardly of the cross drive mechanism so that the opposite drive wheels can be conveniently connected thereto or removed therefrom, and so that the mounting arrangement to the frame can be made smaller or simplified thereat.